The present invention relates to a combustion control device for a heater, and more particularly to a device for controlling fuel combustion in a heater.
The passenger compartment or cabin of a motor vehicle is generally heated by a heat source employing the cooling water of the internal combustion engine on the motor vehicle. However, in cold weather, it takes time to increase the temperature of the cooling water, and hence the compartment cannot be heated quickly.
Japanese Laid-Open Patent Publication No. 61-157422 discloses a vehicle heater device in which fuel is combusted by a burner separate from the internal combustion engine and heat generated by the fuel combustion is recovered by a heat exchanger to supply heating air to the compartment. In the above-noted vehicle heater device, the burner has an atomizing glow plug for atomizing fuel and an igniting glow plug for igniting atomized fuel. A controller including a bridge circuit and a comparator is employed to control supplied electric power to keep the temperatures of the atomizing glow plug and the igniting glow plug in the burner at respective predetermined temperature levels.
According to the above-noted vehicle heater device, the temperatures of the atomizing and igniting glow plugs are controlled at the respective temperature levels, as described above. The atomizing temperature varies from fuel type to fuel type, and if the temperature of the atomizing glow plug is low when fuel of a high atomizing temperature is used, the fuel may not be sufficiently atomized, and a combustion failure may result.